REx Completes Asteroid Touch-And-Go

Pablo Tucker
October 22, 2020

A NASA spacecraft touched down on the rugged surface of the Bennu asteroid on Tuesday, grabbing a sample of rocks dating back to the birth of our solar system to bring home. The samples from Bennu will help scientists understand how planets formed and life began. Otherwise, they will prepare for another attempt in January 2021.

"This unbelievable first for Nasa demonstrates how an incredible team from across the country came together and persevered through incredible challenges to expand the boundaries of knowledge", highlighted Nasa administrator Jim Bridenstine. "Our industry, academic, and global partners have made it possible to hold a piece of the most ancient solar system in our hands". After successful stowage, the spacecraft will slowly drift away from Bennu to a safe distance, where it will stay until its departure in 2021 for the Return Cruise Phase back to Earth.

"Today, we've advanced both science and engineering and our prospects for future missions to study these mysterious ancient storytellers of the solar system", said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, adding that the primordial rock had been witness to the solar system's history.

The goal was to collect at least 1.7 ounces of fine-grained material, but the spacecraft can carry up to 4.4 pounds, Heather Enos, OSIRIS-REx deputy principal investigator at the University of Arizona said.

Now, scientists will check if the spacecraft has managed to collect enough samples by analyzing images and mass measurement using the onboard cameras known as SamCam. Although brief, the Touch-And-Go, or TAG, event was years in the making. The first indication will be provided by before-and-after imagery of the target site, which will show how much of its surface was disturbed by the burst of gas. The gas should have stirred up dust and pebbles on Bennu's surface, some of which should have been captured in the TAGSAM sample collection head.

While the spacecraft's October mission was a historic success for NASA, the probe may have to meet up with Bennu again. That's about the equivalent of a full-size candy bar.

"We're going to be looking at a whole series of images as we descended down to the surface, made contact, fired that gas bottle, and I really want to know how that surface responded", Lauretta said. MapCam was responsible for searching the asteroid for a suitable place to collect the sample. The objective is to collect a sample of at least 60 g. The differences in the pre-touch and post-touch moments of inertia will allow engineers to measure the mass of the sample within the TAGSAM collection head.

A total of 60 grams (2 oz) of asteroid material is expected to be collected, although TAGSAM could collect as much as two kilograms. "If our confidence is high, we'll make the decision to stow the sample on October 30". The spacecraft's collector head is located on an 11-foot-long robotic sampling arm-think an air filter in an older model car-perfect for collecting particulates. That will likely be at a backup site, called "Osprey", which is another relatively boulder-free area inside a crater near Bennu's equator.

If all ends well, OSIRIS-REx will be the first-ever mission to return samples of rock from the birth of the solar system, giving researchers the chance to ask (and answer, hopefully) completely new questions about where the Earth and its neighbors come from. After its 2016 launch from Cape Canaveral in Florida, it arrived at Bennu's position in December of 2018. Regardless of how many tries it takes, the samples won't return to Earth until 2023 to close out the $800-plus million quest.

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